types of bones
- cylindrical in shape, being longer than it is wide
- leverage
long bone
mature bone cells located in space called a lacuna
osteocytes
formation of bone
ossification (osteogenesis)
dense outer layer on every bone that appears smooth and solid
compact bone
zone is bone tissue, also known as metaphysis: transition from epiphysis and diaphysis
ossification zone
- no easily characterized shape and does not fit any other classification
- protect internal organs
irregular bone
bone matrix building cells, found in growing portion of bone including endosteum and periosteum
osteoblasts
- centers created in epiphyses by osteoblasts
- secondary ossification appear later
- replacement of cartilage by bone continues until cartilage, except in the epiphyseal plate and the articular cartilage, has been replace by bone
secondary ossification center formation (through adolescent)
made up of a honeycomb of small, needle-like or flat pieces of bone called trabeculae
spongy bone
region closest to the epiphyseal end of the plate and contains small chondrocytes within the matrix
resting zone
- cube-like in shape, being approximately equal in length, width, and thickness
- provide stability, support, while allowing for some motion
short bone
(RANDOM) when more resorption than deposition occurs
osteoporosis
- embryonic mesenchyme cells aggregate
- cells differentiate into osteochondral progenitor cells
- the cartilage model is surrounded by perichondrium
cartilage model formation (week 9 embryonic)
- spongy and compact bone are fully developed, and the epiphyseal plate has become the epiphyseal line
- only cartilage present is the articular cartilage at the ends of the bone
adult bone
chondrocytes are older/larger and situated closer to diaphyseal end of plate. Longitudinal growth a result of cellular division in proliferative zone and maturation of cells in this zone
hypertrophic zone
- typically thin, it is also often curved
- points of attachment for muscles; protectors of internal organs
flat bone
the only mitotic bone cells, found in the deep layers of the periosteum and the marrow, become osteoblast
ostogenic cells
- blood vessels grow into the enlarged lacunae.
- osteoblasts and osteoclasts migrate in
- the primary ossification center forms
- osteoblasts transform the calcified cartilage of the diaphysis into spongy bone
- osteoclasts remove bone from the center of the diaphysis to form the medullary cavity, and cells within the cavity specialize to form red bone marrow
primary ossification center formation (birth - 3mo)
the cartilage on the diaphyseal side of the plate is replaced by bone
ossified bone
chondrocytes are dead due to calcified matrix. Osteoblasts secrete calcifying matrix. Zone connects epiphyseal plate to diaphysis. Growth occurs as osseous tissue is added
calcification zone
- small, round bone that resembles a sesame seed, form in tendons
- protect tendons from compressive forces
sesamoid bone
break down bone to allow reabsorption of calcium and other mineral, found on bone surfaces, originate from white blood cells, not osteogenic cells
osteoclasts
- blood vessels invade the perichondrium surrounding the cartilage model
- osteoblasts produce compact bone on the surface of the cartilage model
- the chondrocytes in the center die, leaving enlarged lacunae
bone collar formation (up to 3mo embryonic)
layers of matrix around a central canal which houses blood vessels, nerves, and lymphatic vessels
lamellae (compact bone)
contains stacks of slightly larger chondrocytes. New chondrocytes made via mitosis
proliferation zone